Bowling pin



oct. 8, 1968 R. A. SMITH 3,404,885

BowL'ING PIN Filed March so, 1966 ATTORNEY 3,404,885 BOWLING PIN RichardA. Smith, Cornwall on the Hudson, N.Y., as-

signor to American Machine & Foundry Company, a corporation of NewJersey Filed Mar. 30, 1966, Ser. No. 538,678 Claims priority,application Great Britain, Apr. 5, 1965, 14,333/ 65 2 Claims. (Cl.273-82) The invention relates to bowling pins and more particularly toan improved method for manufacturing plastic-coated bowling pins and tothe pins so produced.

It has been the conventional practice in preparing plastic-coated woodpins to apply to the wood core a plurality of layers until a plasticcoating of suiicient depth has ben provided. This procedure of applyingthe several layers and generally drying each layer before applying thesubsequent layers, is time consuming, cumbersome and expensive .andoften results in a plastic coating which delaminates from the pin coreunder the rigorous impact conditions of use.

The present invention is concerned with an improvement in the art ofmanufacturing plastic-coated bowling pins wherein the surface claddingcomprises a single polymeric composition. Specifically the invention isdirected to a novel synthetic plastic cladding comprising a caprolactamor nylon composition. More particularly the composition comprises apreferred copolymer of caprolactam and an alkyl ester of an acrylicacid. The resultingbowling pin is attractive as molded .and requires noadditional finishing to make it acceptable commercially, and it has amarked increase in durability which makes it superior to any knownplastic coated wood pin.

The present invention summarized in essence, is concerned with themanufacture of plastic-coated wood core bowling pins in which a singleplastic comprising caprolactam is applied to the wood core therebyavoiding the need for an impregnant or prime coating for the wood, forsealer coats, and for top coats all of which heretofore were considerednecessary, in addition t-o the main protective coating, in order toprovide a commercially acceptable bowling pin. Although the presentinvention involves primarily encasing wood bowling pin cores, theinvention also has advantageous applications to other bowling pin coresof other materials, eg., plastic, including foamed plastic, and metal.The invention may also be employed in conjunction with reinforced coressuch as those utilizing mesh fabric envelopes, e.g., nylon webbing, overthe pin core.

It is an object of the present invention to provide a relatively lesscostly plastic-coated bowling pin of substantially increased useful lifeand resistance to soilage and at less cost in which a single compositionis utilized as the plastic layer.

It is a further and more specific object of the present invention toprovide a bowling pin containing as the sole surface cladding a singlelayer of synthetic resin comprising a copolymer of caprolactam and analkyl ester of acrylic acid on the bowling pin core.

Additional objects and advantages will become apparent as thedescription of the invention progresses.

In order that the manner in which these and other objects are attained,in accordance with the invention, can be better understood, reference ismade to the .accompanying drawing wherein:

' United States Patent Oce Patented Oct. 8, 1968 FIG. 1 is verticalelevational view partly in section, of a bowling pin having a woodenbody on which, in accordance with the invention, a protective claddingcomprising caprolactam is molded.

In order that the method of the invention can be best understood, thegeneral structure of the finished bowling pin will first be describedwith reference to the drawing. It will be understood that the presentinvention is concerned essentially with the improvement comprising abowling pin with a plastic cladding in which essentially, a singlesynthetic resinous composition is applied over the core; saidcomposition comprising a caprolactam resin.

In the embodiment illustrated, the pin 5 comprises a pin body 6 of mapleor other hardwood, however, although metal such as magnesium or aluminumor plastic foam cores may also suitably be employed. The core is encasedin accordance with the invention with a cladding or cover 7. Inutilizing the single composition layer as taught by the presentinventive concept, it is unnecessary to follow the prior art techniqueof pretreating the core with a plurality of layers including a primerimpregnant composition to permeate the surface of the Wood and a sealercoat in addition to the thick cushioning coat which generally consistedof ethyl cellulose and thereafter followed with a top coat or finishingcoat. A single layer of caprolactam preferably a copolymer ofcaprolactam and ester of acrylic acid is used in lieu of the multiplecoat system heretofore required. The term an acrylic acid includesacrylic acid itself, methacrylic acid, ethacrylic acid and the like.Such esters include, for example, the alkyl, ammo alkyl hydroxyalkyl andthe like esters of acylic acid. Specific illustrative compounds areethylacrylate, butyl acrylate, Z-ethylhexyl acrylate, methylacrylate,methyl-methacrylate, ethylmethacrylate, butyl methacrylate isobutylmethacrylate, lauryl methacrylate, stearylmethacrylate,dmethylaminoethyl methacrylate, t-butylaminoethyl methacrylate,hydroxyethyl methacrylate, hydroxypropyl methacrylate, butylenedimethacrylate and the like. Particularly good results appear from theuse of the caprolactam-ethyl acrylate copolymer.

In the preferred embodiment of the invention, the caprolactam-acrylateester copolymer is cast or injection molded directly over the core; noprimer layer or mpregnant is employed nor is desirable. The coatingproduces a smooth, glossy, attractive appearance so that a finish or topcoat is not required, although for some applications, it may beoptionally desirable to apply a thin top coat film, e.g., for extragloss or to modify friction characteristics. If desired, the resin layermay be contoured so that a thicker layer is formed at the head and bellyregions, 8 and 9, respectively, where abuse and wear is most severe,although preferably, the peripheral layer is made uniform because itdoes not add appreciably to the amount of needed resin and a uniformlayer aids in promoting balance.

The caprolactam copolymers which may be employed in providing thecladding for the bowling pins, in accordance with the invention, :areavailable commercially and may be obtained, for example, from AlliedChemical Corporation, New York.

The polycaprolactam copolymers contemplated are preferably those havingan ester proportion of from about 10 percen-t to about 25 .percent witha corresponding proportion of from about percent to about 75 percentcaprolactam.

In applying the coating to the pin cores, any of various suitableprocedures such as casting the synthetic resinous liquid around the corein commercially available molding machines may be employed. Thefollowing preferred procedure has been successfully utilized:

(1) Metal support pins are positioned at each end of the wood core at 10and 1l.

(2) The wood core with support pins is placed in a suitable mold.

(3) The copolymer is injection molded over the wood core.

(4) The copolymer-clad core is removed from the mold or press. At thistime, the metal -support end pins may be removed automatically ormanually.

(5) The sprue and any polymer ash are removed.

(6) A top plug, preferably molded of the same copolymer as the cladding,is cemented in the hole at at the top of the pin using a suitableadhesive eg., nylon adhesive CPA 619A (Goodrich Tire & Rubber Co.,Chemical Division, Akron 16, Ohio) may be used to -achieve adhesion.

(7) The base of the bowling pin may be finished either by:

(a) A groove is cut in the base, as is standard practice with commercialbowling pins, and a molded plastic base is cemented in place; or

(b) The base can be molded as an integral part of the cladding as shownat 12, by using a properly contoured modified metal support pin duringthe molding opera tion. In this case, the only operation would beremoval of flash.

(8) When the molded copolymer cladding has a commercially acceptablecolor and dirt repellency, the usual neck bands and insignia are placedon the pin. A durable, red pigmented, moisture curable polyurethanecoating system may be used for this purpose, A solvent system to promoteadequate adhesion contributes to durability of the markings.

When it is desired to utilize a topcoat for added soil repellency and/orintensity of color, for example, the copolymer cladding may be given lasuitable topcoat, e.g., a white pigmented, moisture curing polyurethanefilm which utilizes a proper solvent system to promote adhesion. Redneck stripes and the insignia may be then added, as described above.

The following examples, in which the parts recited are parts by weight,are provided in order that the invention may be better understood. Theexamples are illustrative only and should not be interpreted asindicative of limitation on compounds or conditions stated. In eachexample, unless otherwise stated. a plastic cladding of 50 mils isapplied to the bowling pin cores. The over all cycle time generally canvary from about 75 seconds to two minutes.

Example l Metal support pins are attached to each end of a wood core ofsuitable dimensions, as shown in FIG. 1. The support pins have from twoto four gates which distribute and control the flow of polymer. The moldis so constructed that polymer can be introduced from the top of thepin, the bottom of the pin, or from both ends. The preferred techniques,and that used in the example provided, it to gate the polymer by meansof the top metal support pin. The wood core preformed and suitablyfinished and with support pins attached is placed in the holding pins ofa suitable constructed mold which is mounted in an injection moldingpress, such as, for example, New Britain, Ankewerke Reciprocating ScrewInjection Molding Machine, Model 385, New Britain, Conn.

A copolymer of caprolactam-ethylacrylate 80:20 by weight is injectedover a period of about -50 seconds at a temperature of 4about 550 F.,extrusion nozzle temperature into the mold at about 1l0120 F. around thewood core applying a substantially uniform layer of about 50 mils.

After a brief cooling period of `about 45 seconds (total cycle timeincluding injection, cooling and empty dwell in 90 seconds), the moldedlarticle is removed, the metal pins, ash and sprue :are removed and atop plug is inserted at the head. A set of pins made in this manner aretested and found to have an exceptional life exceeding 10,000 lines ofplay.

Example 1I Example I is repeated except that the copolymer introducedinto the extrusion .press is pigmented with a 0.5 percent TiOZ pigmentbased on the total weight of the polymer.

The product has an excellent white lustre and durability comparable tothe pins described in Example I.

Example III The procedure of Example I is repeated except that theresinous composition used is an :20 caprolactamunidecanoic lactamcopolymer, i.e., no acrylic acid ester monomer is involved. While theresulting product did not have durability equal to the pins producedaccording to Example I, the product life at over 7,000 lines wasnevertheless far superior to present commercial pins.

Example V The procedure of Example II is repeated with the exceptionthat la caprolactam-methylmethacrylate 80:20 copolymer is used. Aproduct having a life substantially superior to commercial bowling pinswas attained.

Example Vl The procedure of Example II is repeated except that acopolymer of 75:25 caprolactam-ethylacrylate is substituted. Exceptionalresults, even superior to the product of Example I is obtained.

Example VII The procedure of Example II is repeated using instead acopolymer of :10 capro]actam-ethylacylate. The bowling pin was not asdurable as that of Example II, nevertheless, has a life exceeding 8,000lines of play.

Randomly selected, samples of bowling pins containing a plastic claddingover maple cores of compositions having formulations of Examples I-VIIwere also -tested on a laboratory impact testing apparatus until thepins had been subjected to a number of blows on the impact testerrepresenting actual rough bowling alley service. In each case, thecoating was superior to the best commercially available plastic-coatedpins prepared by multiple coating systems. The coatings in each casewere unusually free of cracks. They had excellent surface appearance anddirt resistance. In each set, scoring is excellent and constantthroughout the life of the pin. The pins exhibited no loss of coatingmaterial and showed a negligible change in ball-line diameter or loss ofadhesion of the cladding from the core.

It will be apparent to those skilled in the art that variousmodifications may be made in the teaching presented without departingfrom the scope of the invention. Accordingly, the invention is not to belimited 5 6 except insofar as necessitated by the appended claims.References Cited I claim: P 1. A bowling pin comprising a preformed bodyencased UNITED STATES ATENTS in a plastic protective claddingcomposition comprising 2,944,821 7/1960 Mason 273-82 a resinous layer offrom yabout 20 to about 200 mils 5 3,138,574 6/1964 Kohan 26Q-78 minimumoverall thickness, said composition comprising 3,332,939 7/1967 Detoro260-78 t ncgoxllyinit caprolac am and a lower alkyl ester of FOREIGNPATENTS 2. A bowling pin in :accordance with claim 1, wherein 6,403,90210/1964 Netherlands. said lower alkyl ester is ethyl acrylate of about 5to 10 735,332 5/ 1966 Canada.

25 parts by weight and said caprolactam is of about c 95 to 75 parts Ibyweight. RICHARD C. PINKHAM, Primary Examiner.

1. A BOWLING PIN COMPRISING A PREFORMED BODY ENCASED IN A PLASTICPROTECTIVE CLADDING COMPOSITION COMPRISING A RESINOUS LAYER OF FROMABOUT 20 TO ABOUT 200 MILS MINIMUM OVERALL THICKNESS, SAID COMPOSITIONCOMPRISING A COPOLYMER OF CAPROLACTAM AND A LOWER ALKYL ESTER OF ANACRYLIC ACID.